Modelling the movement of transformed cell populations.

The aim of this work was to analyze migrating cell populations, in search of motion models able to accurately describe the features of normal and transformed fibroblast movement, under different experimental conditions. Diverse diffusive models were evaluated, by fitting them to experimental datasets obtained by collecting quantitative data on cell direction and step length under standard culture condition as well as after introduction of a wound in the cell layer. The analysis showed that fibroblast movement has the features of a superdiffusion in all the examined cases, as the squared displacements scale superlinearly with time. The persistent random walk model fits all data from fibroblast populations, although a varying degree of persistence was found under different experimental conditions. For NIH3T3 fibroblasts, high persistence was always observed, while NIHRas fibroblasts showed lower persistence in non wound stimulated cultures compared to stimulated ones. In presence of a wound stimulus, directional analysis allowed to associate persistence with a marked ability of fibroblasts to move, all together, towards a specific direction defined by the wound stimulus. Another superdiffusive model, the Là©vy walk, was not successful in describing NIH3T3 and NIHRas fibroblast populations. The procedures have been made available within MotoCell, a web application previously developed to quantitatively study cell movement, in an effort to generate an effective tool, that can easily perform all the steps of a cell motility study, ranging from cell tracking, to descriptive statistics and model fit analysis.